Radiation-curable coating materials are known. They are coating compositions which are cured using high-energy radiation, especially using UV radiation or using electron beams. With the known radiation-curable coating materials it is possible without problems to prepare coating films which are highly glossy to silkily glossy (degree of gloss of between 100 and 50 units according to DIN 67 530 at a measurement angle of 60.degree.).
In contrast, the production of matt coating films gives rise to great difficulties. There exists a series of proposals for solving this technical problem. According to DE-A-29 47 597, coating materials are employed which contain a combination of radiation-curable and heat-curable binders. Disadvantages when using such coating materials are that a baking step is necessary and, when highly reactive heat-curable components are employed, the coating materials must be stored as multicomponent systems. DE-A-22 44 327 describes a technically very complex process for the production of matt coating films, in which the radiation-curable coating material is cured in a first step in an atmosphere which contains at least 5000 ppm of oxygen and subsequently in a second step in an atmosphere which contains less than 1000 ppm of oxygen, by irradiation with high-energy radiation. According to DE-A-41 18 731, matt coating films are prepared by recoating an already coated area with a radiation-curable coating material which contains matting agents, the radiation-curable coating material being applied in a coat thickness such that the cured coating film has a thickness which is less than the average particle size of the matting agent. This process too is associated with high technical effort, since it requires the application of an additional coat, and requires the thickness of the additionally applied coat to be accurately controlled.
The object of the present invention was to provide radiation-curable coating materials with which it is possible, without great technical effort, to prepare matt coating films.
It has been possible, surprisingly, to achieve this object by the provision of radiation-curable coating materials which are characterized in that they contain
A a synthetic resin containing from 1.5 to 5 mol/kg, preferably from 3.6 to 4.5 mol/kg, of ethylenically unsaturated double bonds of which not more than 10%, preferably not more than 5%, are vinyl groups, or a mixture of such synthetic resins, and PA0 B a compound of the general formula Ar--O--R.sub.1 --O--CO--CR.sub.2 .dbd.CH.sub.2, where Ar is an optionally substituted aryl radical, preferably a phenyl radical, R.sub.1 is an alkylene radical having 1 to 6 carbon atoms, preferably an alkylene radical having 1 to 3 carbon atoms, very preferably a --CH.sub.2 --CH.sub.2 -- radical, and R.sub.2 is a hydrogen atom or an alkyl radical having 1 to 3 carbon atoms, preferably a hydrogen atom or a methyl radical, or a mixture of such compounds,
from 10 to 70%, preferably from 20 to 60%, by weight of the total quantity of A and B comprising component A and from 30 to 90%, preferably from 40 to 80%, by weight of the total quantity of A and B comprising component B.
Using the radiation-curable coating materials provided in accordance with the invention it is possible, surprisingly and using the application devices and application methods customary for radiation-curable coating materials, to produce matt coating films, especially coating films having a degree of gloss of between 3 and 50 units according to DIN 67 530 (measured at a measurement angle of 60.degree.).